Dive Safe: How to Avoid Decompression Sickness (The Bends)

Scuba diving is an incredible adventure, allowing us to explore the mesmerizing underwater world. However, with the beauty and thrill comes the responsibility of understanding and mitigating the risks involved. One of the most significant dangers a diver faces is decompression sickness (DCS), commonly known as ‘the bends.’ DCS can range from mild discomfort to severe, life-threatening conditions. This comprehensive guide will delve into the causes of DCS, provide detailed steps and instructions on how to prevent it, and ensure you can enjoy your dives safely.

Understanding Decompression Sickness

Decompression sickness occurs when dissolved nitrogen, absorbed by the body tissues at depth due to increased pressure, forms bubbles in the bloodstream and tissues during ascent. At sea level, the pressure is 1 atmosphere (atm). When we descend underwater, the pressure increases by 1 atm for every 10 meters (approximately 33 feet) of seawater. This increased pressure forces more nitrogen into our blood and tissues. The longer and deeper the dive, the more nitrogen is absorbed. The problem arises during the ascent. If you ascend too quickly, the nitrogen cannot be safely expelled through the lungs and forms bubbles, obstructing blood flow and potentially causing damage to tissues and organs. Understanding this process is the first step in preventing DCS.

Key Factors Contributing to DCS Risk:

• Depth and Time: The deeper you dive and the longer you stay at depth, the more nitrogen your body absorbs, increasing the risk of DCS.
• Ascent Rate: Ascending too rapidly doesn’t allow your body to eliminate the nitrogen effectively, leading to bubble formation.
• Repetitive Dives: Doing multiple dives within a short period without allowing sufficient surface intervals can accumulate nitrogen levels, raising your risk.
• Individual Factors: Age, body composition (higher body fat), fitness level, dehydration, and even certain medications can influence your susceptibility to DCS.
• Water Temperature: Cold water can constrict blood vessels, hindering nitrogen elimination.
• Exertion: Heavy exertion during or shortly after a dive can contribute to DCS risk.
• Flying After Diving: Traveling by air shortly after diving can significantly increase the risk of DCS due to the decrease in atmospheric pressure.

Detailed Steps to Avoid Decompression Sickness

Now that you understand the factors contributing to DCS, let’s explore the crucial steps you can take to minimize the risk and ensure safe diving practices. These steps are applicable for recreational diving and should be adhered to strictly.

1. Pre-Dive Planning and Preparation

Thorough pre-dive planning is crucial for a safe dive. This includes assessing conditions, dive plan, dive buddy communication, and gear check.

1. Choose a Qualified Dive Operator: Always dive with a reputable dive shop or operator that prioritizes safety and has well-maintained equipment. Check their credentials and reviews. Look for certified instructors and dive masters.
2. Complete Dive Training: Ensure you are certified by a recognized scuba diving agency (e.g., PADI, SSI, NAUI). Advanced courses will deepen your understanding of dive theory and safety protocols, including managing decompression requirements. Never dive beyond your certification level.
3. Plan Your Dive Carefully:
   • Determine Dive Site: Select a dive site appropriate for your skill level and experience. Consider the depth, currents, visibility, and potential hazards.
   • Establish Depth and Bottom Time: Use dive tables or a dive computer to plan your dive within no-decompression limits. Never exceed these limits. Learn to correctly interpret and utilize your dive planning tools.
   • Account for Repetitive Dives: If doing multiple dives, calculate the required surface interval between dives to allow your body to off-gas nitrogen. This will change depending on the depth and duration of previous dives.
   • Consider Special Dive Profiles: Learn about multilevel diving techniques to maximize bottom time without exceeding no-decompression limits. This will involve ascending gradually through shallower depths during the dive.
   • Communicate Your Plan: Share your dive plan with your buddy and ensure both of you understand the objectives, emergency procedures, and signals.
4. Check Your Gear:
   • BCD: Ensure your buoyancy control device (BCD) is functioning correctly, including the inflator and deflator mechanisms.
   • Regulator: Check your regulator’s function and ensure you have sufficient air in your tank.
   • Mask & Fins: Verify the fit and condition of your mask and fins, and ensure your mask is clear of smudges or debris.
   • Dive Computer: If using a dive computer, ensure it’s fully charged and set to the correct settings for your dive, including gas mix. Understand how to read and interpret the data during your dive.
   • Wetsuit/Drysuit: Wear appropriate thermal protection based on water temperature.
   • Weights: Adjust your weight for neutral buoyancy at the beginning of your dive.
   • Air Source: Begin each dive with a full tank of air.
5. Buddy Check: Always perform a thorough buddy check before entering the water. Follow the mnemonic BWRAF (BCD, Weights, Releases, Air, Final OK).

2. During the Dive: Adhere to Safe Diving Practices

Once underwater, meticulous attention to your dive plan and environmental conditions is crucial.

1. Maintain Neutral Buoyancy: Learn to control your buoyancy using your BCD and lung control to avoid unnecessary ascents and descents, minimizing the potential for nitrogen absorption issues. A well-controlled buoyancy will also conserve energy and air.
2. Monitor Your Depth and Time: Keep track of your depth and elapsed bottom time. Your dive computer will do this, but be aware of your limits. Do not push the limits of your No-Decompression Time.
3. Stay Within No-Decompression Limits: Adhere to the no-decompression limits provided by your dive computer or dive tables. Never exceed these limits, as this will greatly increase your risk of DCS.
4. Follow Your Dive Plan: Stick to the agreed dive plan with your buddy. Do not deviate without careful consideration of the potential impacts.
5. Communicate With Your Buddy: Regularly communicate with your buddy using hand signals and ensure you are both okay and aware of each other’s air supply and condition.
6. Monitor Air Consumption: Regularly check your air gauge and ensure you have enough air to safely complete the dive and make an ascent with appropriate safety stops. Plan to return to the surface with at least 500 psi of air in your tank.
7. Avoid Exertion: Avoid strenuous activities underwater. Move slowly and deliberately. If you feel short of breath, stop and rest. Exertion can increase the rate at which your body absorbs nitrogen.

3. The Ascent: The Critical Phase

The ascent is arguably the most critical phase of the dive when nitrogen off-gassing occurs. A controlled and slow ascent is crucial to avoid DCS.

1. Ascend Slowly: The maximum ascent rate should be 10 meters (30 feet) per minute (or slower, according to your dive computer), often around 9 meters (30 feet) per minute. Pay careful attention to your dive computer. Do not rush to the surface.
2. Make Safety Stops: A safety stop is a vital part of every dive and is usually done between 3 to 5 meters (10-15 feet) for 3 to 5 minutes. If your dive is deeper than 100 feet a deep stop in addition to the safety stop is recommended (according to your dive computer). Do not skip safety stops! It’s better to be a little later to the surface than to have a dive accident.
3. Maintain Neutral Buoyancy During Ascent: Control your buoyancy using your BCD and lung control to maintain the appropriate depth during ascent, particularly during safety stops.
4. Watch Your Depth and Ascend Rate: Monitor your depth gauge or dive computer closely during the ascent, making sure you stay at the correct rate and level for all required stops.

4. Post-Dive Procedures

Post-dive practices are essential to fully recover from a dive and reduce the risk of delayed onset DCS.

1. Stay Hydrated: Drink plenty of water after each dive. Dehydration can thicken your blood, hindering the elimination of nitrogen.
2. Avoid Alcohol: Avoid alcohol immediately after diving. Alcohol dehydrates the body and could complicate symptoms of DCS.
3. Avoid Strenuous Exercise: Refrain from strenuous exercise immediately after a dive. Give your body time to recover.
4. Surface Interval: Take adequate surface intervals between dives. The longer the interval, the more nitrogen will be eliminated. Allow several hours between dives for deeper dives.
5. Avoid Flying After Diving: Wait at least 12 hours after a single no-decompression dive or 18 hours after multiple no-decompression dives before flying. For dives that require decompression stops, you should wait a minimum of 24 hours. Some guidelines suggest 24-48 hours are preferable for all divers. Consider the increased risk of DCS when travelling in non-pressurized aircraft.
6. Monitor for DCS Symptoms: Be vigilant for any signs of DCS, such as joint pain, fatigue, dizziness, numbness, or tingling. If you experience any of these, seek medical attention immediately.
7. Log Your Dive: Record the details of your dive in a dive log, including depth, bottom time, gas mix, and any other significant information.

Additional Considerations

Beyond the above steps, consider these extra elements for a safer diving experience:

• Nitrox Diving: If certified, consider diving with Nitrox, which contains a higher percentage of oxygen and lower nitrogen than air. This can extend no-decompression limits. It is important to understand and be properly trained in Nitrox diving procedures.
• Dive Computer Training: Take a dive computer course to fully understand how to use its features. A dive computer gives real-time dive information, assists with safe ascent calculations, and can track multiple dives.
• Physical Fitness and Health: Maintain a good level of physical fitness, avoid diving when unwell, and consult your doctor if you have any medical conditions that might affect diving safety.
• Respect Environmental Conditions: Be aware of currents, waves, and visibility. Do not dive if conditions are beyond your comfort level.
• Emergency Preparedness: Know the emergency procedures for DCS, including how to contact emergency services and how to administer first aid. Carry a first aid kit and have emergency contact information handy.

Recognizing the Symptoms of Decompression Sickness

It’s essential to be able to identify the symptoms of DCS. Prompt recognition and treatment can reduce the severity of the condition. Some common signs and symptoms of DCS include:

• Joint Pain: This is the most common symptom and often presents as deep, aching pain in the limbs, usually near the joints. It can be mild to excruciating.
• Skin Rashes: Skin rashes or mottled skin that may appear itchy, often described as a ‘cutis marmorata’ rash.
• Fatigue: Unusual fatigue or exhaustion that is more severe than what would normally be expected after a dive.
• Dizziness or Vertigo: A feeling of being unsteady, lightheaded, or spinning.
• Numbness or Tingling: Tingling, numbness, or paralysis in any part of the body, typically in the limbs.
• Headache: A persistent and severe headache.
• Shortness of Breath: Difficulty breathing or chest pain.
• Changes in Mental Status: Confusion, disorientation, or altered level of consciousness.
• Visual Disturbances: Blurred vision, double vision, or other visual problems.
• Loss of Coordination: Difficulty with balance or fine motor skills.
• Nausea and Vomiting: A feeling of sickness or vomiting.
• Unconsciousness: Loss of consciousness in severe cases.

If you suspect DCS, seek immediate medical attention. Do not delay in going to the nearest Emergency Room or hyperbaric chamber. Provide as much detail as you can about your dive (depth, time, ascent rate) to medical professionals. Early treatment significantly improves the chances of a full recovery. Recompression therapy in a hyperbaric chamber is the most effective treatment for DCS.

Conclusion

Scuba diving offers an unparalleled opportunity to experience the underwater world, but it requires meticulous planning, safe diving practices, and a deep understanding of the physiological risks involved. By diligently following the detailed steps outlined in this guide, you can significantly reduce your risk of developing decompression sickness and enjoy countless safe and memorable dives. Remember that prevention is always better than cure. Dive safe, and explore responsibly.